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传统的土压力分析仅考虑了土体饱和强度对土压力产生的贡献,忽略了基质吸力及其变化对土压力的影响。运用非饱和土有效应力原理和饱和土朗肯土压力公式推导了非饱和土朗肯土压力公式,结合Iverson降雨入渗解析解,推导出降雨入渗条件下非饱和土压力公式。该公式将降雨入渗时的非饱和土压力表示为时间和深度的函数,更符合实际情况。研究结果表明:采用该方法计算得到的土压力值相对于传统计算结果偏大,作用点偏高;此外,随着降雨的发生、入渗和停止,主动土压力呈现“减小-增大-减小-稳定”趋势,被动土压力呈现“增大-减小-增大-稳定”趋势,该现象由降雨过程中基质吸力改变所致。由该公式获得的土压力分布及变化规律可用于挡土工程结构的设计。
The traditional earth pressure analysis considers only the contribution of soil saturation intensity to earth pressure, ignoring the influence of substrate suction and its variation on earth pressure. Based on the effective stress principle of unsaturated soil and the formula of Rankine soil pressure, the formula of Rankine soil pressure in unsaturated soil is deduced. Based on the analytic solution of Iverson rainfall infiltration, the formula of unsaturated soil pressure under rainfall infiltration is deduced. The formula expresses the unsaturated earth pressure during rainfall infiltration as a function of time and depth, which is more in line with the actual situation. The results show that the earth pressure calculated by this method is larger than the traditional calculation result and the action point is high. In addition, with the occurrence of rainfall, infiltration and stoppage, the active earth pressure shows “decrease-increase - decrease - steady ”trend. The passive earth pressure shows the trend of“ increasing - decreasing - increasing - stabilizing ”, which is caused by the change of substrate suction during rainfall. The earth pressure distribution and variation obtained by this formula can be used in the design of retaining structure.